re: #107 Slumbering Behemoth

My understanding is that “sudden” is oft thought of as archaic (or poetic) and that the better term is “suddenly”. “All of a sudden” harkens back to this older use of “sudden”.

My lord, we have
Stood here observing him: some strange commotion
Is in his brain: he bites his lip, and starts;
Stops on a sudden, looks upon the ground,
Then lays his finger on his temple, straight
Springs out into fast gait; then stops again,
Strikes his breast hard, and anon he casts
His eye against the moon: in most strange postures
We have seen him set himself.

[Henry the VIIIth, Act III]

(* shrugs *)